Blog 2

A number of conversations I remember from Dayton last year resolved around the resolution of the then proposed Az/El Rotor project.  A number of comments from well-meaning hams was that a resolution of only 1 degree was inadequate, 0.1 degree was needed.  That may be the case for a large permanent installation with long high gain antennas but for a portable system using small portable antennas 1 degree is actually overkill.  While talking with Tim of Arrow Antennas, he told me that the Alaskan dual band handheld satellite antenna had a 3dB bandwidth of 20 degrees.

Speaking of Arrow antennas, I really like the design; they are very light weight but sturdy and are easy to assemble and use.

Anyway, the new design uses an optical encoder to provide the input to the micro-controller to track position.  The Single Axis design uses an encapsulated magnetic red switch.  An analysis of stepper motors was done and it was decided to stay with the geared DC motors as used in the Single Axis product design.  The higher current, larger size and increased cost of a stepper motor and driver all added up to make it the wrong choice for this product.  Of course stepper motor control is like a ‘zillion’ times easier than the complex state machine needed to accurately control multiple small DC gear head motor.

More to follow

 

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